Semiconductor quantum dots (QDs) are fascinating nanoscopic structures for photonics and future quantum information
technology. However, the random position of self-organized QDs inhibits a deterministic coupling in devices relying on
cavity quantum electrodynamics (cQED) effects which complicates, e.g., the large scale fabrication of quantum light
sources. As a result, large efforts focus on the growth and the device integration of site-controlled QDs. We present the
growth of low density arrays of site-controlled In(Ga)As QDs where shallow etched nanoholes act as nucleation sites.
The nanoholes are located relative to cross markers which allows for a precise spatial alignment of the site-controlled
QDs (SCQDs) and the photonic modes of high quality microcavites with an accuracy better than 50 nm. We also
address the optical quality of the SCQDs in terms of the single SCQD emission mode linewidth, the oscillator strength
and the quantum efficiency. A stacked growth of strain coupled SCQDs forming on wet chemically etched nanoholes
provide the smallest linewidth with an average value of 210 μeV. Using time resolved photoluminescence studies on
samples with a varying thickness of the capping layer we determine a quantum efficiency of the SCQD close to 50 % and an oscillator strength of about 10. Finally, single photon emission with associated with g(2)(0) = 0.12 of a weakly
coupled SCQD - micropillar system will be presented.

In this paper, we present experimental results from site-selected single quantum dots that have
undergone a number of intermixing process steps via rapid thermal annealing. We show that the
intermixing process blueshifts the dot's emission spectrum without affecting the linewidth as well as
decreasing its biexciton binding energy and s-p shell spacing. The anisotropic exchange splitting is
shown to have undergone a sign inversion implying that the splitting had gone through zero.
Intermixing provides another nanoengineering tool for the design of scalable solid-state photon and
entangled photon pair sources.

A large vertical electric field can be used to linearly change the fine-structure splitting of a single InGaAs/GaAs quantum
dot by over 100 μeV. In each single dot an avoided crossing is observed, where the magnitude of the splitting reaches
a minimum value. We confirm in experiment that polarization-entangled photon pair emission occurs from quantum dots
tuned in this manner.

We show that the carrier capture from the optical confinement layer into quantum dots (QDs) can strongly limit the
modulation bandwidth ω-3 dB of a QD laser. Closed-form analytical expressions are obtained for ω-3 dB in the limiting cases of fast and slow capture. ω-3 dB is highest in the case of instantaneous capture into QDs, when the cross-section of carrier capture into a QD σn = ∞. With reducing σn, ω-3 dB decreases and becomes zero at a certain non-vanishing value σnmin. This σnmin presents the minimum tolerable capture cross-section for the lasing to occur at a given dc component j0 of the injection current density. The higher is j0, the smaller is σnmin and hence the direct modulation of the output power is possible at a slower capture. The use of multiple layers with QDs is shown to considerably improve the modulation response of the laser - the same ω-3 dB is obtained in a multi-layer structure at a much lower j0 than in a single-layer structure. At a plausible value of σn = 10-11 cm2, ω-3 dB as high as 19 GHz is attainable in a 5-QD-layer structure.

Colloidal nanocrystals, i.e. quantum dots synthesized trough wet-chemistry approaches, are promising nanoparticles for
photonic applications and, remarkably, their quantum nature makes them very promising for single photon emission at
room temperature. In this work we describe two approaches to engineer the emission properties of these nanoemitters in
terms of radiative lifetime and photon polarization, drawing a viable strategy for their exploitation as room-temperature
single photon sources for quantum information and quantum telecommunications.

The near-infrared (NIR)-emitting quantum dots (Qdots) have great potential for the use in biological imaging and
diagnostic applications. In our work, a facile method was developed for the preparation of high quality, water-soluble,
and NIR-emitting CdSeTe alloyed Qdots (A-Qdots) with L-cysteine (L-cys) as capping agent. By changing the size and
the composition of the A-Qdots, the photoluminescent quantum yields (QYs) can reach as high as 53% and the emission
color can be tuned between visible and NIR regions. Based on the fluorescence of the A-Qdots selectively quenched in
the presence of Cu2+, the NIR-emitting CdSeTe A-Qdots were applied in ultrasensitive Cu2+ sensing. Furthermore, the
prepared CdSeTe A-Qdots have been successfully applied for cell imaging, glucose and cholesterol assay, which
demonstrates the great potential of the Qdots for biological applications. In order to improve the biocompatibility of the
CdSeTe A-Qdots, new water-soluble CdSeTe/ZnS core-shell Qdots (CS-Qdots) with excellent NIR emission were
synthesized in aqueous solution. The prepared CS-Qdots not only possessed high QYs but also exhibited excellent
photobstability and favorable biocompatibility. Moreover, the CS-Qdots showed high electrogenerated
chemiluminescence (ECL) signal. These characteristics showed their potential applications in cell imaging and
biosensing with high sensitivity.

We developed ratiometric optical oxygen sensors to probe the oxygen consumption during epileptic events
in rat brain slices. The oxygen sensors consist of the sensing part of phosphorescence dyes (Platinum (II)
octaethylporphine ketone) and reference part of nanocystal quantum dots (NQDs) embedded in polymer blends,
with pre-designed excitation through fluorescence resonance energy transfer (FRET) from NQDs to the oxygen
sensitive dyes (OSDs). The ratiometric FRET sensors with fast temporal response and excellent bio-compatibility
are suitable for real time quantitative dissolved oxygen (D.O.) probes in biological microenvironment. Coating the
sensors onto the micro-pipettes, we performed simultaneous oxygen probes at pyramidal and oriens layers in rat
hippocampal CA1. Different spatiotemporal patterns with maximum D.O. decreases of 9.9±1.1 mg/L and 4.9±0.7
mg/L during seizure events were observed in pyramidal and oriens layers, respectively.

We report on pump-probe mode-mismatched photothermal lens experiments of metallic nanoparticles water solutions.
We show that metallic nanoparticles colloids exhibit nonlinear absorption effects related to attraction or repulsion forces
that result from the interaction with the electromagnetic radiation. Gold and iron oxide nanoparticles show a double
peak Z-scan shape that is associated to the presence of attraction forces. We calibrate the experiment using the linear
absorption values of the samples obtaining their corresponding nonlinear absorption coefficients.

In this study, we present a facile route to fabricate large-scale arrays of GaAs nanowires (NWs) with high aspect ratio on
transparent substrates. It is demonstrated that the monolayer of SiO2 nanoparticles can be effectively used as etch masks
for the inductively coupled plasma (ICP) etching process. To form the monolayer of SiO2 nanoparticles on the GaAs
substrate, the concentration and temperature of the SiO2 colloidal dispersion solution as well as the interface wetting of
the GaAs substrate are investigated. By adjusting the ICP etching conditions, the high-aspect-ratio GaAs NWs with
lengths of 4.3μm and cross-sections of 70nm are successfully fabricated. Furthermore, the fabricated GaAs NWs are
massively transferred onto the transparent substrate at low temperature. The SEM observation and the X-ray diffraction
spectrum reveal that the transferred GaAs NWs have vertically aligned morphology and good crystal property.

Excitons of CdTe quantum tetrapods are theoretically analyzed. Individual electron and hole states are calculated by solving one-particle Schrödinger equation by the finite element method with the single-band effective-mass approximation and exciton states are obtained by exact diagonalization of the configuration interaction Hamiltonian. Spatial symmetries of the exciton states are related to those of the one-particle states by group theory and verified by numerical calculation. Then optical transition spectra are calculated and compared with available experimental data.

We describe two different approaches to growing precisely positioned InP nanowires on InP wafers. Both of these
approaches utilize the selective area growth capabilities of Chemical Beam Epitaxy, one using the Au catalysed Vapour-Liquid-Solid (VLS) growth mode, the other being catalyst-free. Growth is performed on InP wafers which are first
coated with 20 nm of SiO2. These are then patterned using e-beam lithography to create nanometer scale holes in the
SiO2 layer to expose the InP surface. For the VLS growth Au is then deposited into the holes in the SiO2 mask layer
using a self-aligned lift-off process. For the catalyst-free growth no Au is deposited. In both cases the deposition of InP
results in the formation of InP nanowires. In VLS growth the nanowire diameter is controlled by the size of the Au
particle, whereas when catalyst-free the diameter is that of the opening in the SiO2 mask. The orientation of the
nanowires is also different, <111>B when using Au particles and <111>A when catalyst-free. For the catalysed growth
the effect of the Au particle can be turned off by modifying growth conditions allowing the nanowire to be clad,
dramatically enhancing the optical emission from InAs quantum dots grown inside the nanowire.

As a type-II heterostructure with exclusive hole confinement GaSb/(Al,Ga)As QDs are an ideal candidate for
a QD based memory device operating at room temperature. We investigated different Antimony-based QDs in
respect of localization energies and storage times with 8-band-k•p calculations as well as time-resolved capacitance
spectroscopy. In addition, we present a memory concept based on self-organized quantum dots (QDs) which could
fuse the advantages of today's main semiconductor memories DRAM and Flash. First results on the performance
of such a memory cell are shown and a closer look at Sb-based QDs as a storage unit is taken.

The growth procedures and device applications of GaSb/GaAs quantum dots (QDs) are investigated in this report.
The influence of As flux on the GaSb QD morphologies and optical characteristics has revealed the importance of
precise Sb/As flux control during Sb post-soaking procedures after GaSb deposition. With optimized GaSb QD growth
conditions and long-term Sb post soaking procedure, room-temperature operation light-emitting diodes (LEDs) and
high-temperature operation quantum-dot infrared photodetectors (QDIPs) are demonstrated. The results have revealed
the possibilities of type-II GaSb QDs in the applications of optical devices.

GaSb quantum dots (QDs) have been grown epitaxially on GaAs in the Stranski-Krastanov (SK) mode. By variation of
the Sb/Ga-V/III flux ratio, the growth temperature, and the nominal coverage the QD dimensions and optoelectronic
characteristics can be tuned. These modifications enable dense lying dots with a density up to 9.8 x 1010 cm-2. The
position of the photoluminescence (PL) peak can be varied between 0.850 and 1.378 μm by precise control of growth
parameters. To raise the PL intensity and QD laser output power samples with a stack of GaSb QD layers are grown on
GaAs wafer. A GaSb-QD-laser with a 8-fold stack and an emission wavelength around 0.900 μm is realized with a
differential quantum efficiency of 54%.

Based on atomistic analysis and kinematic diffraction theory, it has been previously predicted that quantum dot heights
can be extracted from RHEED intensity profiles along the chevron tails (Feltrin A. and Freundlich A, J. Cryst. Growth
301-302, 38-41-2007). Here we report the existence of such periodic RHEED intensity fringes and demonstrate
experimentally the possibility of monitoring real time the evolution of the average dot-size in the archetype InAs/GaAs
system. The methodology when combined with RHEED information on the dot surface coverage and facet orientation is
shown to provide a full metrology of self assembled quantum dots and could be valuable in assessing the QD growth
kinetics and improving process reproducibility.

This paper investigates the fully coupled piezoelectric models for determining strain fields, piezoelectric potentials, and
optical properties of wurtzite InGaN quantum dots (QDs). Through the calculations, we find that the semi-coupled
model clearly overestimates the piezoelectric potential, and the transition energy difference increased with increases in
the dot size and indium composition. Consequently, the semi-coupled model causes a great amount of distortion in
predicting the optical properties of InGaN QDs, compared to the fully coupled piezoelectric models.

The optical and structural properties of InAs/GaAs quantum dots (QD) are strongly modified through the use of a thin (~
5 nm) GaAsSb(N) capping layer. In the case of GaAsSb-capped QDs, cross-sectional scanning tunnelling microscopy
measurements show that the QD height can be controllably tuned through the Sb content up to ~ 14 % Sb. The increased
QD height (together with the reduced strain) gives rise to a strong red shift and a large enhancement of the
photoluminescence (PL) characteristics. This is due to improved carrier confinement and reduced sensitivity of the
excitonic bandgap to QD size fluctuations within the ensemble. Moreover, the PL degradation with temperature is
strongly reduced in the presence of Sb. Despite this, emission in the 1.5 μm region with these structures is only achieved
for high Sb contents and a type-II band alignment that degrades the PL. Adding small amounts of N to the GaAsSb
capping layer allows to progressively reduce the QD-barrier conduction band offset. This different strategy to red shift
the PL allows reaching 1.5 μm with moderate Sb contents, keeping therefore a type-I alignment. Nevertheless, the PL
emission is progressively degraded when the N content in the capping layer is increased.

Surface enhanced Raman radiation of crystal violet dye has been studied by modulating the
localized surface plasmon effect of silver nanoparticles. In the experiment, a buffer layer of silicon
dioxide (SiO2) was established between crystal violet dye and silver nanoparticles. With a probe of
laser beam of 532 nm in wavelength, it was found that the intensity of the Raman scattering
significantly depended on the thickness of SiO2 layer. A maximum Raman-radiation intensity occurred
with a 10nm-thicked SiO2 layer. The experimental observation shows a possible modulation of surface
enhanced Raman radiation by a proper dielectric buffer.

Highly ordered and highly density nanopore arrays of anodic aluminum oxide template was prepared by a two-step
anodization method and with the assistance of ultrasonic. Well-aligned nanopore arrays were obtained perpendicular
to the surface of aluminum. The first step anodization was carried out under 0.4 M oxalic acid for one hour, and the
anodized film was removed by chemical etching, than the sample was anodized again for 40 minute under the same
conditions as the first anodization and with ultrasonic. The results of aluminum oxide films were characterized by
scanning electron microscopy, and the microstructure of the anodic aluminum oxide membrane indicating that the
nanochannel arrays prepared with the assistance of ultrasonic are better than those in ordinary way related to the pore
aligned and pore density.

We demonstrated a fast and easy way to synthesize Ag nanoparticles (NPs) on ZnO
nanowires (NWs) and silicon substrates by an electroless (EL) plating approach. ZnO NWs
used here were grown via vapor-solid (VS) mechanism at 560 °C for 30 min. The stability to
oxidation of these EL-produced homogeneous Ag NPs on ZnO nanowires was investigated by
surface enhanced Raman spectroscopy (SERS), showing that the attachment of thiol to the Ag
surface can slow down the oxidation process, and the SERS signal remains strong for more
than ten days. Furthermore, we examined the surface oxidation kinetics of the Ag NPs as a
function of NPs size and size distribution by monitoring the oxygen amount in the composites
using energy dispersive x-ray (EDX). Results indicate that the EL plated Ag NPs show faster
oxidation rates than those produced by e-beam (EB) evaporation in air. We attribute this to
the fact that the EL produced silver particles are very small, in the 20 nm range, and thus have
high surface energy, thus enhancing the oxidation. These studies provide extensive
information related to the Ag NP oxidation rates, which can help in extending the Ag lifetime
for various applications.

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Journal of Applied Remote SensingJournal of Astronomical Telescopes Instruments and SystemsJournal of Biomedical OpticsJournal of Electronic ImagingJournal of Medical ImagingJournal of Micro/Nanolithography, MEMS, and MOEMSJournal of NanophotonicsJournal of Photonics for EnergyNeurophotonicsOptical EngineeringSPIE Reviews